-LRB- CNN -RRB- -- Clashes broke out Saturday as far-right groups from across Europe gathered in Denmark for a rally they said was meant to make their governments act against the threat of Islamic extremism .

Violence flared in the port city of Aarhus as a small group of far-left protesters broke off from a march staged to counter the right-wing rally , said Georg Husted , a spokesman for Aarhus police .

Protesters carrying masks pulled up paving stones and started throwing them and other missiles , he said .

One police officer suffered minor head injuries after he was struck by a bottle , Husted said , but no civilians were hurt or damage caused to buildings .

Police arrested 25 people following the violence , said Husted , most of them from extreme left-wing groups .

Between 200 and 300 people attended the far-right rally , according to police estimates , while about 5,000 people gathered for the anti-fascist demonstration .

The left wing march was peaceful apart from the actions of a few `` hard core '' protesters who wanted to cause trouble , Husted said .

The far-right rally brought together protesters from the Danish Defense League , as well as smaller groups from Scandinavian countries , Germany , Poland , Eastern Europe and the United Kingdom .

Those attending want to send a `` clear message to the leaders of Europe , '' according to the English Defence League -LRB- EDL -RRB- , one of the organizers of the far-right event .

`` Our governments and our media behave as if Islamic extremism exists only in the head of a few extremists , and claim that it is unfair to make the connection between Islam and extremism , '' an online EDL statement said .

`` This is ridiculous , just as it is ridiculous to claim that anyone who criticizes Islam must be an extremist in their own right . We believe in fair criticism of Islam and in the defence of our cultures , our nations , and the rights and freedoms that they have long protected . ''

Husted said ahead of the rally that police were focused on making sure the day passed peacefully without confrontations between the groups .

`` We are going to support anyone who is going to talk and to demonstrate for what they feel , according to Danish law , '' he said .

In its statement , the EDL said it does not believe that `` the way to combat extremism is with more extremism . '' Racists and neo-Nazis are not welcome , and those supporting the rally have signed an agreement against extremism , it said .

The British government has previously banned some marches by the EDL , whose members are widely seen as holding extremist views .

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NEW : A police officer is injured as a handful of far-left and far-right demonstrators clash

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NEW : Some 200-300 members of European far-right groups rally in Aarhus , police say

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NEW : About 5,000 people turn out for a counter anti-fascist demonstration , police say

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The far-right English Defence League says it wants to highlight the threat of Islamic extremism